I grew these a couple of years ago but can't offer much advice. I love the blooms from most of the family Fabaceae. The flowers are not large but are pretty in a gentle way. Mistakes I made:
I started them in jiffy pots in the greenhouse and planted them out in mid-late April. We still have some coolish nights at that time and they seemed to stand still until the weather was consistently warm at night. If I ever plant them again I will wait until a little later.
Also, I had them in a bit of shade and they were leggy and had few flowers. Full sun is probably better.
Maybe someone more successful with them can provide insight on what works.
Gotta love those legumes!
Alana